1. Field of the Invention
This invention relates to circuitry for testing the operation of relay drivers and, more particularly, testing circuitry capable of complete operation without causing the relay to be actuated.
2. Description of the Prior Art
Many systems have been developed in order to assure the operation of the relay driver circuitry. However, most of these test circuits require the transmission of a test current through the coil of the relay in order to assure that the relay driver is operating properly. Although such systems are designed to transmit a small test current with the expectation that the relay will not be actuated, it is often found that the relay threshold may be exceeded and unwanted relay actuation may occur. In addition, this testing system requires additional circuitry in order to provide the particularly desired control and testing sequence.
In an attempt to eliminate some of the inherent difficulties encountered with the low current level test method, other test systems have employed the transmission of short duration pulses to the relay in order to test the relay driver circuitry. By employing pulses of short duration, the relay typically will not respond to the voltage and will not be switched. However, this system depends on the precise pulse duration and, in addition, requires added circuitry in order to attain the desired results.
Therefore, it is the principal object of the present invention to provide a relay driver testing system which requires no additional circuitry and assures that the relay coil is not actuated.
Another object of the present invention is to provide a relay driver testing system having the characteristic features described above which assures dependable operation and complete testing of all components of the relay driver.
Other and more specific objects will in part be obvious and will in part appear hereinafter.